Original U.S. Constitution

[No State shall ...] make any Thing but gold and silver
Coin a Tender in Payment of Debts; ...

Note that there is no such prohibition against Congress, or
any delegated power to make anything legal tender. Congress was
originally understood to have no power to make anything legal tender
outside of federal territories, under Art. I Sec. 8 Cl. 17
and Art. IV Sec. 3 Cl. 2,
but in 1868 a Supreme Court packed by Pres. Ulysses S. Grant, in the Legal
Tender Cases, allowed Congress to make paper currency issued
by the U.S. Treasury, backed by gold, legal tender on state territory,
a precedent that remains controversial to this day, when courts allow
paper currency not backed by anything to be considered "legal tender".

Seventh Amendment

The only money amount in the Constitution or its amendments is
in the Seventh Amendment:

In Suits at common law, where the value in controversy shall
exceed twenty dollars, the right of trial by jury shall be preserved,
and no fact tried by a jury, shall be otherwise re-examined in any
Court of the United States, than according to the rules of the common
law.

In 1789 the "dollar" was a coin, the Spanish taler,
containing 371.25 grains of pure silver, or 416 grains of silver of
standard (coin grade) purity. A troy ounce, the standard measurement
unit for precious metals, is 480 grains, so a "dollar" contains 0.7734
troy ounce of pure silver, and 20 such coins would weigh 17.3333 troy
ounces and contain 15.46875 troy ounces of pure silver. One can use the
Oanda Currency Converter
below to find out what the current value of that amount of bulk silver
would be in federal reserve notes. For example, on June 15, 2000, it
would be about $87.71 in federal reserve notes. However, keep in mind
that the world trading price for gold or silver is the bulk, wholesale
price, for ingots, in minimum quantities of 400 troy ounces, and the
trading is generally only a tranfer of title and not a physical
delivery of the ingots, for which an additional transport charge may be
made. As single coins it would have about twice that bulk value, so the
constitutional threshold under the Eighth Amendment would be closer to
$176 in federal reserve notes. That would be the minimum "value in
controversy" that would preserve the right to trial by jury in a civil
case.

Documents

Excerpt
from 1923 Congressional Record — The Federal Reserve and
several large banks deliberately contracted to extend credit to the
agriculture industry for the purpose of eliminating many farmers.

The
Gold Confiscation Of April 5, 1933 — Unconstitutional act of
Congress and President Roosevelt.

Money
as Debt Quotations — Revealing statements from public figures.

31
USC 5103, defining legal tender. However, it only constitutionally
applies to non-state U.S. territory, such as federal enclaves created
under Art.
I Sec. 8 Cl. 17 or incorporated territory under Art. IV
Sec. 3 Cl. 2.

What
Is A "Dollar"? An Historical Analysis Of The Fundamental
Question In Monetary Policy, by Edwin Vieira.

Trashing
the Constitution: How misconstruction of the monetary powers and
disabilities subverted the Founding Fathers’ intent, speech
of Edwin Vieira before the Rotary Club of New York, March 25th, 2003.

The
Money Issue, memorandum of law by Larry Becraft.

A Caveat Against Injustice, or, An
Inquiry into the Evils of a Fluctuating Medium of Exchange,
Roger Sherman (1752) — By the author of the Tender Clause of the U.S.
Constitution.